Measurement of Available Lead and Cadmium in Soil by ICP-MS with Ultrasonic Extraction

According to determination of available forms of lead and cadmium in soil, the contents of lead and cadmium were directly determined with DTPA as extracted by inductively coupled plasma-mass spectrometry (ICP-MS). The effects of ultrasonic extraction time, dilution time of extraction agent and the analytical conditions were investigated, and the elimination of matrix interference was compared. The results show that the available lead and cadmium have good linearity in the concentrations of 1-200 μg/L, and the detection limits of the method are 0.019 mg/kg and 0.001 4 mg/kg, respectively, the relative standard deviation is less than 6%. The accuracy and precision of the method were verified by analyzing national standard reference materials. There was no significant difference between this method and the national standard method （GB/T 23739-2009） by t test, the relative standard deviation is less than 5%. This method has characteristics of convenient, low detection limit, high accuracy and good precision, which can be applied to determine available forms of lead and cadmium in large batches agricultural pollution soil.